During the operation of DC motors, the occurrence of electrical interference or disturbances constitutes a problem. In particular, the occurrence of electrical interference, in control circuits that are configured for electronic commutation of currents flowing in a DC motor, can negatively affect control of the DC motor. Such electrical disturbances or interference encompasses both high-energy transient pulses and low-voltage interference in the frequency range from 50 Hz to 20 kHz, with amplitudes of 6 V peak-to-peak.
Protective circuits used in the existing art encompass varistors and LC filters or filter capacitors to protect DC motors from electrical interference. The varistors serve to absorb the high-energy transient pulses, and the LC filters or filter capacitors serve to filter out low-voltage interference. The necessary size, restricted working temperature, and limited service life of LC filters or filter capacitors, however, makes them complicated to use and of only limited utility. The use of varistors is complex and cost-intensive because of the varistor dimensions that are required.